use c# threadpool or task to call a function and get return value
cmd = new OleDbCommand { Connection = con, CommandText = "Select recid,col_A,col_B from tblData"};
dr = cmd.ExecuteReader();

if (dr.HasRows)
{
   cmdRec = new OleDbCommand { Connection = con };
   while (dr.Read())
    {
    sReqResult = DoProcessing(dr["col_A"].ToString(), dr["col_B"].ToString(), dr["PARAM2"].ToString());
        sSql = "update tblData set STATUS='" + sReqResult + "' where recid = '" + dr["recid"] + "'";
    cmdRec.CommandText = sSql;
    cmdRec.ExecuteNonQuery();
    }
}
dr.close();

while(true)
        {
            string enabled = null;
            currentInstance = OrderManager.getCurrentInstance();
            SqlCommand command = new SqlCommand("Select OrderNumber, BatchStatus from dbo.Orders where StatusChanged='1'", connection1);
            SqlDataReader reader = command.ExecuteReader();
            if (reader.HasRows)
            {
                while (reader.Read())
                {
                    Int64 orderNum = (Int64)reader[0];
                    int index = linqForOrderIndex(orderNum);
                    string batchStatus = (string)reader["BatchStatus"];
                    SqlCommand statusChangedFalse = new SqlCommand("Update dbo.orders Set StatusChanged = '0' where OrderNumber = '" + orderNum + "'", connection2);
                    switch (batchStatus)
                    {
                        case "Untouched":
                            currentInstance.Orders[index].batchStatus = "Untouched";
                            break;
                        case "Batch Ready":
                            currentInstance.Orders[index].batchStatus = "Batch Ready";
                            break;
                        case "Shipped":
                            currentInstance.Orders[index].batchStatus = "Shipped";
                            break;
                        case "Error":
                            currentInstance.Orders[index].batchStatus = "Error";
                            break;
                    }
                    statusChangedFalse.ExecuteNonQuery();

                    Thread.Sleep(1000);

                    reader.Close();
                    reader = command.ExecuteReader();
                }

                currentInstance.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Normal,
                    new Action(
                        delegate()
                        {
                            currentInstance.refreshTreeFilters();
                            currentInstance.refreshOrderCounts();
                            currentInstance.batchReadyView();
                        }
                    ));
            }
      }

if (dr.HasRows)
{
    object someDataToWorkWith = "data";

    Action<object> resultCallback = (theResults) =>
    {
        // Executed once the workItem is finished.
        // Work with and/or present the results here.
    };

    WaitCallback workItem = (dataOrSomeDetails) =>
    {
        // This is the main async-part. Work with or fetch data here.
        // You can also access any variables from the containing method.
        // When finished working, execute callback:
        resultCallback("someResults");
    };

    ThreadPool.QueueUserWorkItem(workItem, someDataToWorkWith);
}